The present invention pertains generally to the field of navigation systems, and in particular, the invention relates to a position system used for navigation inside a building, structure or location using, in part, existing artificial light sources.
Conventional navigation systems are known that can assist/guide a user to a location. For example, GPS (global positioning system) is widely used in positioning and navigation applications. GPS is a radio navigational aid using multiple satellites in high orbit around the earth with position fixes determined by range and range-rate measurements. GPS provides extremely accurate position and velocity information to users around the world. Satellites, maintained by the U.S. government, transmit coded radio frequency (RF) signals to earth-based GPS receivers. Highly accurate (within several meters) position determinations (i.e., longitude and latitude coordinates) are based on measurements of propagation times of the RF signals from the satellites.
A GPS receiver unit maybe incorporated in a mobile handset to receive signals from the GPS satellites. These signals are used to identify the position of the handset. The GPS receiver may also include or be linked to a digitally stored map to provide navigation instructions to the user. However GPS receivers need line of sight to satellites so they are potentially unreliable inside cars, buildings, and under foliage. Also GPS receivers themselves may be expensive.
Another approach consists of installing radio frequency (RF) transmitters, e.g., Bluetooth-based transmitters, in a building. Bluetooth wireless technology is a low-cost, low-power, short-range radio link for mobile devices and for WAN/LAN access points. It offers digital transmissions of both voice and data over the globally available 2.4 GHz ISM (Industrial, Scientific and Medical) band. The transmission range of Bluetooth transmitters is typically less than 10 m. A wireless receiver placed in the vicinity of a transmitter will receive the corresponding signal thus identifying its position. Radio frequency transmission, however, is sensitive to interference from other RF devices. The frequency bands of the RF devices are also heavily regulated by the U.S. Federal Government.
It has been proposed in the past to use existing lighting infrastructure in buildings to transmit signals by modulating the light output of light sources (see, e.g., U.S. Pat. Nos. 3,900,404 and 6,198,230). In such systems, a photosensitive detector is used to receive the transmitted information. Input data (audio, analog data, or digital data) is fed to a modulation circuit with modulates the light output (see FIG. 1). The transmission bit-rate is limited by the maximum modulation frequency of the output of the light source. Furthermore the light sources must be tied into a network to receive the data input.
As discussed above, for in-building positioning and navigation applications, GPS is not reliable and the GPS receivers are expensive. The installation of radio frequency transmitters throughout a building to form a positioning system requires the installation of additional infrastructure. Furthermore the use of radio frequency is subject to regulations. Also conventional methods for transmitting data by modulating the light output require a network to send the data to the light source driver. In these systems, the transmission data-rate is limited by the maximum modulation frequency of the light output.
Accordingly, there is a need for a in-building navigation system that solves the shortcomings of the above-described systems.
One aspect of the present invention uses existing lighting infrastructure (e.g., fluorescent lamps and fluorescent lamp drivers) in a building or structure to form an in-building positioning system. This arrangement typically does not require any additional infrastructure cost. The lighting infrastructure may be any type of light source, such as fluorescent, halogen or incandescent light sources. It is noted that incandescent light sources will require a modulation driver circuit. The building or structure can be any type of house, office, arena, complex or location that include some sort of artificial lighting.
Various embodiments of the invention can be used to add in navigating a user within a building. Application examples of this invention include:
finding a particular store in a mall;
finding a room or a specific facility in a hotel;
locating an item in a supermarket or a warehouse;
finding a gate of a specific facility in an airport; and
locating a seat in sports arena.
One embodiment of the present invention is directed to a positioning system used for navigation inside a building, structure, arena or location. Light sources used as beacons to transmit unique codes by modulating their light output. The transmitted codes are decoded by an optical receiver and are used in combination with a digital building map stored in the receiver to provide navigation instructions to the user within a building (e.g., mall, hotel or airport).
In one embodiment, a navigation system includes a light source having a driver and an encoder. The driver and the encoder are coupled to the light source so that the light source produces a modulated light signal in accordance with a predetermined signature. A receiver is provided having a photosensitive detector capable of detecting the modulated light signal and a decoder capable of decoding the predetermined signature. A controller is communicatively coupled to the receiver, a memory and an output device. The controller is arranged to receive the decoded predetermined signature, based upon the decoded predetermined signature, obtain at least one navigation instruction stored in the memory, and output the navigation instruction using the output device.
In another embodiment, an optical receiver is provided for operation with the navigation system.
Yet another embodiment is directed to a navigation system including means for producing a light signal having a signature, means for decoding the signature from the light signal and means for providing a navigation instruction in accordance with the signature.
These and other embodiments and aspects of the present invention are exemplified in the following detailed disclosure.